This invention pertains to a method of operating insertion machines, and in particular such machines wherein a vacuum is used at various machine stations to ultimately insert material into an envelope.
U.S. Pat. No. 2,325,455 to A. H. Williams relates to a multi-station inserter which performs numerous functions including extracting an envelope from an envelope supply station and transporting it to an inserting station where the envelope is opened. The machine also extracts pieces of insert material from one or more insertion supply stations and transports the aggregate material so extracted to the inserting station where it is inserted into the envelope.
The inserter described above provides a pneumatic mechanism for handling insertion material at each insertion supply station. In this regard, a pair of vacuum cups at each station applies suction to a lowermost piece of vertically stacked material at the station in order to deflect the lowermost piece for extraction by a gripper jaw. Each pair of vacuum cups for each insertion supply station is ultimately connected to a single control valve which simultaneously governs the transmission of the vacuum through the pairs of vacuum cups at each insertion supply station. In this respect, the control valve is operated once during each operating cycle of the inserter machine.
In an analogous manner, the inserter provides a similar pneumatic mechanism at the envelope supply station to engage successive envelopes. A second similar control valve is also timed to the machine operating cycle; and applies a vacuum to similar vacuum cups at the envelope supply station to engage a selected envelope.
In addition to the above-described inserter features, pneumatic means are also provided at the inserting station to draw front and back portions of each envelope away from one another in order to open the envelopes for reception of the aggregate insertion material. In this regard, vacuum cups are positioned above and below the plane of travel of the envelope at the inserting station; and, a third valve, timed with the operating cycle of the machine, operates the vacuum cups to open and close the envelope at the inserting station.
As indicated above, the vacuum supply is turned on or off at particular points, or increments, in the machine's operating cycle. These points are typically expressed in degrees of the machine's rotational cycle, each full cycle being 360.degree.. The vacuum may be applied to each particular type station only during a range of degrees, or a "window," which corresponds to an appropriate stage in the inserting machine.
Since all the insertion supply stations are governed by a single valve, it follows that all of the insertion supply stations have the same vacuum timing. This is true regardless of the number or nature of such stations.
In operating in the above-described manner it often would be advantageous to vary the vacuum timings. For example, in the case of the insertion supply stations it would generally be economical to change the timing from station to station depending on the characteristics of the insertion material being handled at the respective stations. By way of illustration, heavier insertion material stacked at one station may require a longer vacuum duration than lighter material stacked at another station. Other material characteristics which may prompt variable vacuum timing include the degree of material warpage and flexibility. Also, the relative conditions of the operating environment, such as the degree of humidity, may have an impact on the desirable duration of vaccum timing.
In the past it has been possible to vary vacuum timings for all the insertion supply stations collectively by having a mechanic internally adjust the timing of the appropriate control valve. Of course, all the supply stations connected to the valve would be uniformly affected by this change in the valve timing. Moreover, it is unfortunate that a machine operator is not able to make the timing adjustments, but, instead is dependent upon the availability and skill of a mechanic to make the mechanical adjustments to the valve.
Accordingly, an object of this invention is to provide a timing control system to selectively vary the application of vacuum to individual stations of an insertion machine.
An advantage of this invention is the capability for an operator to externally select the variable vacuum application for individual stations without the need for internal structural adjustment by a mechanic.
A further advantage of this invention is the conservative and economical use of a vacuum in an inserter depending on the variable operating considerations for different stations of the machine.